I've started using Twitter (who hasn't) and I'm hoping I'll reach the critical mass of followers to actually find use for the service. As for now I've been using netvibes to throw my twit in the air. I find it a bit too much to actually start paying for a client (Twitterific) so I started searching for an alternative.
At first I thought Chitter would allow me to twitter from within iChat, but it only changed 'mood message'.
Eventually I settled for Spaz but I'd love to have a native OS X app with the same features.